This application claims an invention which was disclosed in a provisional application filed Nov. 14, 2006, entitled “Apparatus and Systems for Integration of a Sensor into a Wheel”. The benefit under 35 USC § 119(e) of the United States provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference.
The purpose of this invention is to integrate a sensor into a wheel. This is advantageous as various factors, including particularly tire pressure, can be more easily monitored in this fashion. The sensor of our invention may be attached to the wheel or may be integrated into the wheel. An air passageway between the tire cavity and the sensor may or may not be employed.
FIG. 1 shows a section of a one-piece wheel assembly 1 without sensor. The one-piece wheel assembly 1 consists of a wheel 2 with tire 3 and inflation valve 4. The circular wheel 2 includes a rim portion 5, formed coaxially on opposite ends thereof with outwardly flaring circumferential flange sections disposed to be engaged by the beads of a tubeless tire. A transverse wall section, disc portion 6, extends transversely of the axis of the circular wheel 2 and its rim 5, and includes a central opening (hub bore area 9) disposed coaxially on said axis. Also illustrated are drop center area 7, valve hole 8, and hub bore area 9. The tire 3 and rim 5 form a tire air chamber 10 that contains a pressured fluid (usually air).
FIG. 2 shows a section of a two-piece wheel assembly 11 without sensor. The two-piece wheel assembly 11 includes a wheel 12 with tire 3 and inflation valve 4. Parts of wheel 12, as before, include a rim portion 5, a transverse wall or disc portion 6, and a hub bore area 9. Also illustrated, and forming a typical part of a two-piece wheel assembly, is rim flat area 13. The tire 3 and rim 5 form a tire air chamber 10 that, as with the one-piece wheel assembly, contain a pressured fluid (usually air).
Two-piece wheels 12 are usually used when a bead lock 14 or run flat device (not shown) are utilized in the two-piece wheel assembly 11. The wall section of two-piece wheels consists of two major parts, an outer portion (or rim hall) 15 and inner portion (or rim hall) 16. The two portions 15 and 16 are sealed with an o-ring 17 placed between confronting surfaces of the two portions 15 and 16 so as to prevent air from escaping out of tire air chamber 10 (thereby creating a sealed space including tire chamber 10). Studs 18 and nuts 19 bolt the two rim halves 15 and 16 together.
Current technology for use of sensors employs several different configurations and methodologies. First, sensors may be embedded in tire 3 where they are invisible to inspection and generally inaccessible. (This version is not illustrated). Second, as illustrated in FIG. 3, a sensor portion 20 may be placed with the tire interior (air chamber 10) connected to a valve portion 21. The valve portion 21 goes through valve hole 8 in one-piece wheel 2. The sensor portion 20 measures the air pressure in tire air chamber 10 and sends a signal to a monitor (not shown) in the cab portion of the vehicle. Third, as illustrated in FIG. 4, a sensor 22 can be employed anywhere within the tire cavity 10. (The tire 3 and tire chamber 10 are not shown in FIG. 4 so that sensor 22 and bracket or band 23 can be seen). Sensor 22 can be attached with a bracket or band 23 or by any other method inside the tire chamber 10. Fourth, as illustrated in FIG. 5, another technology attaches a sensor 25 directly to the inflation valve 4. Fifth, a sensor may be contained in a sensor body so that it is exterior to the tire chamber, but detects pressure therein via an air channel portion extending through the sensor body from the tire chamber to the sensor. (See, e.g., U.S. Pat. No. 7,089,147).
However, all of the aforesaid methods and apparatus have disadvantages. Sensors inside the tire cavity are subject to harsh environments including elevated temperatures and impact damage. In addition, such sensors are difficult to assemble when inside the tire, there is limited access in case of malfunction, and sensors can be damaged during tire assembly or tire removal. Sensors in the tire cavity may also cause wheel imbalance, may have signal interference due to the tire and or wheel structure, and are expensive to install and maintain. Sensors that attach to inflation valves are susceptible to damage from curbs, rocks or other obstructions on the road; require removal in order to inflate or deflate tires; can cause the inflation valve to leak; and are highly visible and more susceptible to theft. In addition, some sensors require the vehicle to be driven in order to be activated, many are too bulky, and some require special brackets or hardware to attach. Finally, many of the current art place sensors in locations (outwardly from the axis of the wheel) where they are subject to radical centrifugal forces.
Thus, as previously noted, the purpose of this invention is to avoid the disadvantages of prior art by integrating a sensor into a wheel. If the sensor is embedded in the wheel rim or disk, then numerous advantages can be realized. First, integrated sensors are well protected and less susceptible to environmental fluctuations including but not limited to, temperature, humidity, harsh chemicals, theft, and/or impact loads. Second, sensors on or in the wheel are easier to assemble and remove. If the sensor is mounted on the “weather” side of the rim (any portion of the wheel that is exposed to weather—as opposed to the tire-side of the rim) then the tire does not have to be removed to gain access to the sensor. Third, the sensor can be located closer to the wheel hub to reduce centrifugal forces and reduce wheel imbalance. Fourth, a sensor can be attached to the wheel or embedded in the wheel more securely and without excessive components/hardware. Fifth, a sensor mounted onto or into the wheel results in less weight, especially when part of the wheel material is removed in order to attach the sensor, to create a mounting void in which the sensor can be mounted, or to create an air passageway/duct to the sensor. Sixth, the placement of the sensor will result in less signal interference. Seventh, sensors in the wheel are less likely to leak air. Eighth, the sensor can be smaller due to the fact that there will often be no need for a bulky and protective sensor housing. Ninth, cost is reduced due to lack of a sensor housing or the reduction in size of such housings, lack of brackets and other mounting hardware, smaller batteries and not having to re-mount tires in order to mount/service sensors.